This invention relates generally to methods and apparatus for coronary imaging, and more particularly to methods and apparatus for computed tomographic (CT) imaging of specific artery branches with reduced motion artifacts.
Computed tomographic (CT) imaging and magnetic resonance imaging (MRI) can be utilized to visualize coronary arteries, which are very tiny structures. However, visualization of these structures is difficult, because different coronary arteries are subject to different motions throughout a cardiac cycle. For example, the right coronary artery (RCA) remains on a single plane and undergoes large displacements. The left anterior descending (LAD) vessel, on the other hand, lies on a curved surface and its branches follow different motion patterns. Known electrocardiograph (EKG) driven reconstruction methods and apparatus do not take these variations into account, so it has been difficult to achieve optimum visualization of at least some coronary arteries.
There is therefore provided, in one aspect, a method for imaging a selected coronary artery. The method utilizes a computed tomography (CT) imaging system having a rotating gantry, a detector array on the rotating gantry, and a radiation source on the rotating gantry configured to project a beam of radiation towards the detector array through a patient""s heart. The method includes utilizing a data compilation of low motion cardiac phases and corresponding coronary artery branch segments to select a cardiac phase corresponding to the selected coronary artery branch segment. A volume of the patient""s heart is scanned with the CT imaging system to acquire projection data. The volume includes at least the selected coronary artery branch segment, and the acquired projection data includes projection data acquired during the selected cardiac phase of a plurality of cardiac cycles of the patient. An image including at least the selected coronary artery branch segment is reconstructed, selectively utilizing the projection data acquired during the selected cardiac phase of the plurality of cardiac cycles to effectively reduce motion artifacts of the selected coronary artery branch segment on the reconstructed image.
In another aspect, a computed tomography (CT) imaging system is provided. The CT imaging system has a rotating gantry, a detector array on the rotating gantry, and a radiation source on the rotating gantry configured to project a beam of radiation towards the detector array through a patient""s heart. The imaging system is configured to utilize a data compilation of low motion cardiac phases and corresponding coronary artery branch segments to select a cardiac phase corresponding to a selected coronary artery branch segment. The imaging system is also configured to scan a volume of the patient""s heart to acquire projection data. The volume includes at least the selected coronary artery branch segment and the acquired projection data includes projection data acquired during the selected cardiac phase of a plurality of cardiac cycles of the patient. The imaging system is further configured to reconstruct an image including at least the selected coronary artery branch segment. For image reconstruction, the CT imaging system selectively utilizes the projection data acquired during the selected cardiac phase of the plurality of cardiac cycles to effectively reduce motion artifacts of the selected coronary artery branch segment on the reconstructed image.
In yet another aspect, a computer system is provided that is configured to utilize a data compilation of low motion cardiac phases and corresponding coronary artery branch segments to select a cardiac phase corresponding to a selected coronary artery branch segment. The computer system is further configured to read projection data acquired by a computed tomographic (CT) imaging system during a scan of a volume of a patient""s heart. The volume represented by the projection data includes at least the selected coronary artery branch segment, and the acquired projection data includes projection data acquired during the selected cardiac phase of a plurality of cardiac cycles of the patient. The computer system is further configured to reconstruct an image including at least the selected coronary artery branch segment. To do so, the computer system is configured to selectively utilize the projection data acquired during the selected cardiac phase of the plurality of cardiac cycles to effectively reduce motion artifacts of the selected coronary artery branch segment on the reconstructed image.
In still another aspect, a machine readable medium having instructions recorded thereon is provided. The instructions are configured to instruct a computer to utilize a data compilation of low motion cardiac phases and corresponding coronary artery branch segments to select a cardiac phase corresponding to a selected coronary artery branch segment. In addition, the instructions are configured to instruct the computer to read projection data acquired by a computed tomographic (CT) imaging system during a scan of a volume of a patient""s heart. This volume includes at least the selected coronary artery branch segment. The acquired projection data includes projection data acquired during the selected cardiac phase of a plurality of cardiac cycles of the patient. The instructions are additionally configured to instruct the computer to reconstruct an image including at least the selected coronary artery branch segment. To do so, the instructions are configured to instruct the computer to selectively utilize the projection data acquired during the selected cardiac phase of the plurality of cardiac cycles to effectively reduce motion artifacts of the selected coronary artery branch segment on the reconstructed image.